Process of annealing iron articles



Feb. 9, 192e. L 1,512,600

1-1. T, GRAFTON Erm.

.PRocEssl oF 11.111111111111111 IRON ARTICLES med March so 1921 2 sheets-sheet 1 attozneg Feb. 9 1926.

' H. T. GRAFTON ET AL PROCESS oF ANNEALING IRON ARTICLES Filed March 50. 1921 2 Sheets-Sheet 2 V OFFICE.

PROCESS OF ANNEALING IRON ARTICLES.

Application iled'March 30, 1921'. Serial No. 456,914.

To all* 'whom it may Camerun Be it known that HOWARD T. GRAFTON and CARL W. WEESNER, citizens of the United States, both residing at Warren, in the county of Trumbull. and State of Ohio,

\ have invented certain new ,and useful Improvements in Processes of Annealing lron Articles, of which the following is a specification.

Our invention relates to a process for purifying gas, more particularlyfproducergas so as to make the latter adaptable for the annealing of iron articles without staining the same.

Raw producer-gas coming from a -producer, preferably utilizing charcoal-fuel, has

the following composition:

N 4'H2O gnuns per illuminante cu.ft. .2% Gas of'such a composition is notysuitable for'bright annealing since, due to its high kblued edges.

moisture, carbon dioxid and oxygen contents, it is not completely reducing in its effect. It follows therefrom :that gas of such a composition when applied to the annealing of steel plates, will not produce a bright finish which is essentialto the product. Unless the steel plates are free from stains, they must be dlsearded. The oxygen in the gas reacts With the steel plates as follows:

3Fe+202=Fe34 The moisture reacts as follows:

SFe-l-ll-IzO-FeBO-l-lI-lz Both 'of these reactions produce badly The carbon dioxid present in the gas serves to dilute the same and renders it less reducing in its action. If the carbone.

dioxid in converted into carbon monoXid the gas will have considerably increasedreducing-value.

The object of our invention is to purify .producer-gasby decreasing its moisture and carbon dioxid-contents and substantially eliminating the oxygen-content, thereby forming a gas more completely reducing in its effect', and rendering possible its application in an economic and eicient manner to annealingand similar processes.

closed in` a refractory material,

vmovable top and bottom Figure i1 is a side view partly in section.

of the purifying-apparatus;

Y Figu're 2 is an end View .of the same partly in section;

Figure?) is a side view of the purification chambers;,

`Figure 4 is a vertical sectional view of the same, and

Figure 5 is a detail partly in section of a modified preheating chamber.

Referring to the drawings, the apparatus comprises a furnace designated as a whole by the numeral 1 having the customary side and end walls 2 and 3, roof 4, and bottom 4', lire wall 5, and grate 6., The furnace is provided with a fire door 7 and iiue 8. Suspended from the roof 4 by the flanges 12 and protruding therefrom are longitudinally extended purification chambers 9 and 9b suitably connected with each 'other by means of conduits 10 carrying valves 11. The purification-chambers may form a single battery asshown in Figures 2 and 4 or a series as shown in Figure 3. The feedI pipe 13 carries the gas to be purified from a suitably located storagetank 14 to the preheater 15 which is enpreferably the fire Wall 5, adapted to be heated by the furnace-gases. The preheater 15 is integral with the pipe 16 which is substantially outside of the furnace wall 2 'and leads to the purification-chamber 9". The

purification-charhbers 9* and 9b have replates 17 land 18, both preferably hinged as at 19. The bottom plates are provlded with plate-retaining-means 20. v

` The furnace is provided with a tunnel or pit'21 and the purification chambers only partially extend into the same, thereby permitting access at'all times to the chambers. The purified gas passes from the furnace by means of the conduit 22,` The preheater may be in the form of ai U-tube 23 as shown in Figure 5.

The preheater and purification-chambers may be made of any suitable material but ,ple yet eflicient `ber-connections outside of the furnace.

suspended from are preferably formed of wrought iroii-iiiaferial and carry on the outside thereof a fireproof cement coating.

rlhe construction set forth provides a simapparatus. tion-chambers which are always completely occupied with a porous purification-medium free fi'om channels, preferably charcoal, are as above described, longitudinally extended, and protrude from the roof of the furnace, thereby making the chambers accessible from the outside of .the furnace, facilitating cleaning and refilling without disturbing the fire. This arrangement makes it possible to have most of the charpthe chambers 9a and 9b are the roof by means of flanges 12, they may be easily removed in case it becomes necessary to replace them.

Since the reactions that occur in the purification-chambers only take place at or above 500 C. and as all the reactions with the exception of one are endothermic, it' is essential to kdeliver the gas to the purificationchambers as hot as possible and this is advantageously accomplished by passing the gases through they preheater 15. l

In the operation of the apparatus set forth the producer-gas containing considerable quantities of moisture, carbon dioxid and oxygen is passed from the storage-tank` 14, througvi conduit 13 to the preheater 15 located in the fire wall 5 and then through conduit 16 into the longitudinally extended purification chambers 9 and 9", which are substantially completely filled with a porous more particularly,`

purification-medium, preferably charcoal. Any substance which is porous and free from sulfur and acts as reducing medium may be used. Carbonaceous material, and charcoal is preferred. Longitudinally-extended chambers provide a large purification-surface and this is highly desirable. The gas free from contaminating addition fluids such as, steam enters chamber 9b through conduit 16 and passes upwardly through the chamber filled with the purification-medium and into chamber 9a by means of vconduit 10. The gas passes downwardly through chamber 9a and into conduit 22. The direction which the gas takes in its passage through the chambers is inditated by the arrows in Figure 4.

The purification is'efl'ected at a 1temperature of 500 C. or above and we have ascer- Ltained that for the removal ofthev impurities this is the minimum temperature that maybe employed. 'The temperature may be increased above this .to any degree the fui'- l vnace will stand, andthe higher the temperature, th@I greater the efficiency.

While we do not desire to limit our inventiomto -any particular theory as to the action of the charcoal upon the gas, it is 002+ ezco.

As this is a reversible reaction, and the reverse occurs at temperatures lower than 500 C., it is essential to `keep the purification-chambers at a higher ltemperature.

The moisture reacts with the carbon in two different Ways as follows:`

soA

At 500 to 600 C. reaction 1 predom-4 inates; as the temperature rises reaction 2 gradually asserts itself until, at a temperature of 1000 C. and above it occurs exclusively. Both of these reactions are exceedingly endothermic in character.

` The oxygen is removed by combination with the carbon, forming first carbon dioxid which is subsequently changed to carbon inonoxid as heretofore indicated.

It follows from thel above that it is necessary to keep the temperature of the purification-medium as high as possible in order to convert the carbon dioxid, moisture and oxygen-contents of the producer-gas from harmful to useful gases. The preheating of the producer-gas is a considerable aid in maintaining the correct temperaturecoiiditions. l

If the producer-gas contains sulfur, this may be efciently removed by passing vthe gas through ferrie hydrate, previous to its` Producer gas made according to our proccss is substantially free from oxygen and contains aquantity of moisture insufficient to stain iron plates when used to anneal the same. The finished gas may contain carbon dioxid not exceeding four per cent, and moisture not exceeding 2 grains per cubic foot. -These figures are, of course, approximate and may vary considerably according to the composition of the raw gas and thel specific conditions of treatment.

The term, iron articles as used' in the claims is intended to cover the different varieties of iron capable of being annealed and particularly, articles made of Steel.

We claim:

1. In a process of annealing iron articles,

tially free Jfrom oxygen and containing a 'quantity of moisture insuicient to stain the iron article.

2. In the fprocess of, annealing iron articles, the use of purified producer gas containing carbon dioxid not exceeding 4%, moisture not exceeding two grains per cubic feet, and substantially free from oxygen.

3. In the 4proces-s of annealing iron 10 articles, the use of purified producer gas containing a quantity .of moisture insuicient to stain'the iron article.

In testimony whereof we hereunto aiix our signatures. i

HOWARD TOLAN GRAFTON. CARL WILLIAM WEESNER. 

